Transiting exocomets detected in broadband light by TESS in the β\beta Pictoris system

We search for signs of falling evaporating bodies (FEBs, also known as exocomets) in photometric time series obtained for $\beta$ Pictoris after fitting and removing its $\delta$ Scuti type pulsation frequencies. Using photometric data obtained by the TESS satellite we determine the pulsational properties of the exoplanet host star $\beta$ Pictoris through frequency analysis. We then prewhiten the 54 identified $\delta$ Scuti p-modes and investigate the residual photometric time series for the presence of FEBs. We identify three distinct dipping events in the light curve of $\beta$ Pictoris over a 105-day period. These dips have depths from 0.5 to 2 millimagnitudes and durations of up to 2 days for the largest dip. These dips are asymmetric in nature and are consistent with a model of an evaporating comet with an extended tail crossing the disk of the star. We present the first broadband detections of exocomets crossing the disk of $\beta$ Pictoris, consistent with the predictions made 20 years earlier by Lecavelier Des Etangs et al. (1999). No periodic transits are seen in this time series. These observations confirm the spectroscopic detection of exocomets in Calcium H and K lines that have been seen in high resolution spectroscopy.Comment: Accepted version updated with correct references to Rappaport et al. (2018) and various typo

The science process for selecting the landing site for the 2020 Mars rover

The process of identifying the landing site for NASA's Mars 2020 rover began in 2013 by defining threshold mission science criteria related to seeking signs of ancient habitable conditions, searching for biosignatures of past microbial life, assembling a returnable cache of samples for possible future return to Earth, and collecting data for planning eventual human missions to the surface of Mars. Mission engineering constraints on elevation and latitude were used to identify candidate landing sites that addressed the scientific objectives of the mission. However, for the first time these constraints did not have a major influence on the viability of candidate sites and, with the new entry, descent, and landing capabilities included in the baseline mission, the vast majority of sites were evaluated and down-selected on the basis of science merit. More than 30 candidate sites with likely acceptable surface and atmospheric conditions were considered at a series of open workshops in the years leading up to the launch. During that period, iteration between engineering constraints and the evolving relative science potential of candidate sites led to the identification of three final candidate sites: Jezero crater (18.4386°N, 77.5031°E), northeast (NE) Syrtis (17.8899°N,77.1599°E) and Columbia Hills (14.5478°S, 175.6255°E). The final landing site will be selected by NASA's Associate Administrator for the Science Mission Directorate. This paper serves as a record of landing site selection activities related primarily to science, an inventory of the number and variety of sites proposed, and a summary of the science potential of the highest-ranking sites

Mutations in the Lipopolysaccharide Biosynthesis Pathway Interfere with Crescentin-Mediated Cell Curvature in Caulobacter crescentus

Bacterial cell morphogenesis requires coordination among multiple cellular systems, including the bacterial cytoskeleton and the cell wall. In the vibrioid bacterium Caulobacter crescentus, the intermediate filament-like protein crescentin forms a cell envelope-associated cytoskeletal structure that controls cell wall growth to generate cell curvature. We undertook a genetic screen to find other cellular components important for cell curvature. Here we report that deletion of a gene (wbqL) involved in the lipopolysaccharide (LPS) biosynthesis pathway abolishes cell curvature. Loss of WbqL function leads to the accumulation of an aberrant Opolysaccharide species and to the release of the S layer in the culture medium. Epistasis and microscopy experiments show that neither S-layer nor O-polysaccharide production is required for curved cell morphology per se but that production of the altered O-polysaccharide species abolishes cell curvature by apparently interfering with the ability of the crescentin structure to associate with the cell envelope. Our data suggest that perturbations in a cellular pathway that is itself fully dispensable for cell curvature can cause a disruption of cell morphogenesis, highlighting the delicate harmony among unrelated cellular systems. Using the wbqL mutant, we also show that the normal assembly and growth properties of the crescentin structure are independent of its association with the cell envelope. However, this envelope association is important for facilitating the local disruption of the stable crescentin structure at the division site during cytokinesis

Impact of depth of response on survival in patients treated with cobimetinib ± vemurafenib: pooled analysis of BRIM-2, BRIM-3, BRIM-7 and coBRIM.

BackgroundThis pooled analysis investigated the prognostic value of depth of response in two cohorts of patients with BRAFV600-mutated metastatic melanoma treated with vemurafenib or cobimetinib plus vemurafenib.MethodsThe data were pooled from BRIM-2, BRIM-3, BRIM-7 and coBRIM. Association of depth of response with survival was estimated by Cox proportional hazards regression, adjusted for clinically relevant covariates. Depth of response was analysed in previously identified prognostic subgroups based on disease characteristics and gene signatures.ResultsGreater tumour reduction and longer time to maximal response were significantly associated with longer progression-free survival (PFS) and overall survival (OS) when evaluated as continuous variables. Patients with the deepest responses had long-lasting survival outcomes (median PFS: 14 months; OS: 32 months with vemurafenib; not estimable with cobimetinib plus vemurafenib). Cobimetinib plus vemurafenib improved depth of response versus vemurafenib monotherapy regardless of other prognostic factors, including gene signatures.ConclusionsGreater depth of response was associated with improved survival, supporting its utility as a measure of treatment efficacy in melanoma and further evaluation of its incorporation into existing prognostic models. Cobimetinib plus vemurafenib improved outcomes across quartiles of response regardless of prognostic factors or gene signatures and provided durable survival benefits in patients with deep responses

Nutrition and the prevalence of dementia in mainland China, Hong Kong, and Taiwan: an ecological study.

BACKGROUND: Western diets are associated with obesity, vascular diseases, and metabolic syndrome and might increase dementia risk in later life. If these associations are causal, those low- and middle-income countries experiencing major changes in diet might also see an increasing prevalence of dementia. OBJECTIVE: To investigate the relationship of dietary supply and the prevalence of dementia in mainland China, Hong Kong, and Taiwan over time using existing data and taking diagnostic criteria into account. METHODS: Estimated total energy supply and animal fat from the United Nations was linked to the 70 prevalence studies in mainland China, Hong Kong, and Taiwan from 1980 to 2012 according to the current, 10 years, and 20 years before starting year of investigation. Studies using newer and older diagnostic criteria were separated into two groups. Spearman's rank correlation was calculated to investigate whether trends in total energy, animal fat supply, and prevalence of dementia were monotonically related. RESULTS: The supply of total energy and animal fat per capita per day in China increased considerably over the last 50 years. The original positive relationship of dietary supply and dementia prevalence disappeared after stratifying by newer and older diagnostic criteria and there was no clear time lag effect. CONCLUSION: Taking diagnostic criteria into account, there is no cross-sectional or time lag relationship between the dietary trends and changes in dementia prevalence. It may be too early to detect any such changes because current cohorts of older people did not experience these dietary changes in their early to mid-life.There is no specific funding contributing to this study. Yu-Tzu Wu received a PhD scholarship from Cambridge Trust, University of Cambridge. William B. Grant received funding from Bio-Tech Pharmacal (Fayetteville, AR) and the Sunlight Research Forum (Veldhoven) and has received funding from the UVFoundation (McLean, VA), the Vitamin D Council (San Luis Obispo, CA), and the Vitamin D Society (Canada). A. Matthew Prina was supported by the Medical Research Council [grant number MR/K021907/1].This is the final published version. It first appeared at http://dx.doi.org/10.3233/JAD-141926

The Effect of Acute Consumption of Overtime Essential Amino Acids Sports Drink on Delayed Onset Muscle Soreness in the Older Sedentary Population

Essential amino acids are necessary for nutrition whether obtained by digestion of proteins or by oral supplementation of amino acids. The elderly experience loss of skeletal muscles and decrease in their strength and function, which can lead to poor quality of life. Increased quantity and quality of proteins stimulates muscle protein synthesis that can help combat this natural aging process. Purpose: The aim of this study was to see if consumption of essential amino acid drink high concentrations of leucin (2040 mg/serving) during exercise will attenuate the condition of Delayed Onset Muscle Soreness in the elderly. Also, we aimed to assess the degree of muscle flexibility and endurance followed the three-day exercise protocol. We hypothesized that the older participants acutely ingesting the essential amino acid supplement during the exercise regime will have increased physical performance and diminished symptoms of DOMS. Methods: In this study, 16 participants (6 P, 10 EAA-O) completed a health screening visit and an exercise routine (sit, stretch and reach, shoulder flexibility distance, MVC isometric handgrip, push-ups (reps), flexed arm hang (time), cable triceps extension (50% of one repetition max until failure), and a 1.5-mile run, with intermittent consumption of the sports drink) for three consecutive days. The study participants were randomly assigned to either the EAA-O group (6.6g of EAA-O + Gatorade) or the control group (Gatorade-only). The study design is a double blinded study as neither the recording analysis researchers nor study participants were aware of the assigned group. Results: The EAA-O group improved significantly from day one to two in flexed arm hang (p = 0.036) and the 1.5-mile run (p = 0.040). The EAA-O group improved significantly from day two to three in push-ups (p = 0.002), flexed arm hang (p = 0.035), and 1.5-mile run (0.001). The EAA-O group improved significantly from day one to three in push-ups (p = 0.045), flexed arm hang (p = 0.006), 1.5-mile run (p = 0.0003), and the top speed (p = 0.026). The placebo group did not improve significantly in any of the exercise parameters. Conclusions: Results suggest that the Overtime essential amino acid supplementation combined with training improves overall athletic performance in the older sedentary population. Research reported in this publication was supported by a research contract with Calwood Nutritionals and was approved by the ENMU IRB

A Thirty Kiloparsec Chain of "Beads on a String" Star Formation Between Two Merging Early Type Galaxies in the Core of a Strong-Lensing Galaxy Cluster

New Hubble Space Telescope ultraviolet and optical imaging of the strong-lensing galaxy cluster SDSS J1531+3414 (z=0.335) reveals two centrally dominant elliptical galaxies participating in an ongoing major merger. The interaction is at least somewhat rich in cool gas, as the merger is associated with a complex network of nineteen massive superclusters of young stars (or small tidal dwarf galaxies) separated by ~1 kpc in projection from one another, combining to an estimated total star formation rate of ~5 solar masses per year. The resolved young stellar superclusters are threaded by narrow H-alpha, [O II], and blue excess filaments arranged in a network spanning ~27 kpc across the two merging galaxies. This morphology is strongly reminiscent of the well-known "beads on a string" mode of star formation observed on kpc-scales in the arms of spiral galaxies, resonance rings, and in tidal tails between interacting galaxies. Nevertheless, the arrangement of this star formation relative to the nuclei of the two galaxies is difficult to interpret in a dynamical sense, as no known "beads on a string" systems associated with kpc-scale tidal interactions exhibit such lopsided morphology relative to the merger participants. In this Letter we present the images and follow-up spectroscopy, and discuss possible physical interpretations for the unique arrangement of the young stellar clusters. While we suggest that this morphology is likely to be dynamically short-lived, a more quantitative understanding awaits necessary multiwavelength follow-up, including optical integral field spectroscopy, ALMA sub-mm interferometry, and Chandra X-ray imaging.Comment: 7 pages, 4 figures, accepted for publication in ApJ Letters. High resolution images of the cluster can be found at http://hubblesite.org/news/2014/2